Was Pennywise scary? Yes, he was very scary!
Were the kids as good as they needed to be to make this movie work? Yes, they definitely were!
Was the movie as good as everyone was hoping? YES!
Now let's take a deeper look at the movie. The movie was a bit over 2 hours and I think that was a perfect length. It didn't feel dragged out and it never got boring. I think they managed to get just the right length on it and tell the story in the pace it needs to be told in. They have changed quite a few things from the book. They are mostly minor though and doesn't change that much of the main plot. They moved the kids adventures from the 50's to the 80's and of course that gives the movie a different look and feel but it works. To get to Pennywise they now go through the house on Neibolt Street instead of the sewers. It's Ben who knows about Derry's past and not Mike, Mike's parents are dead and a few more things like that. No big deal though and it really doesn't affect the movie or the plot.
Bill Skarsgard is perfect as Pennywise. I know it's not fair to compare him with Tim Curry who played Pennywise in the miniseries but how can I not? Where Bill's version is more scary than funny Tim's is more funny than scary. Some of that is because there are 27 years (is that a coincidence?) between them and a lot has happened when it comes to special effects during those years. But I also think they had very different approaches to what and who Pennywise is and that shows in the movies.
One thing that got me thinking "hmm, how are they going to handle this if/when they do a second movie?" was when Bill at the end of the movie tells Pennywise that he has no power over them any longer since they aren't afraid of him. If that is true, then coming back as adults wouldn't be that big of a problem, right? They know they can kill Pennywise and that they don't need to be afraid, why would then Pennywise be a threat to them? I'm more curious than worried about how they are going to solve this though. I have total confidence in Andy and his crew to make it logical once they start working on the second movie.
I think that the majority of the fans that like the book version will like the movie. As I said the changes don't affect the story and many of the classical scenes are there. We get the Georgie and Pennywise talking in the sewer scene (man this is so much more than what we see in the trailer, and so horrible), the blood in Bev's bathroom is there, times 10, the scene where Bowers cuts an "H" in Ben's stomach is there and so on. We get all the scenes we're expecting.
The casting is there, the script works, Pennywise works, there are quite a few scare-jump-scenes and I truly feel that Andy Muchettie and his team have lived up to the extremely high expectations that were put on them. Good work! Now start working on the second movie!